An expansion cloud chamber was used to measure homogeneous nucleation rates for n-pentanol in argon carrier gas at four nucleation temperatures 292, 282, 272, and 252 K. The nucleation rates range from about 15000 to 400 drops/cm3 s. The data exhibits changes with time that are attributed to the removal of trace impurities by self-cleaning action in the cloud chamber. Data at the highest supersaturation ratio for a given number of drops observed is considered to be closest to true homogeneous nucleation. A comparison of these measurements with data in the literature at similar temperatures and nucleation rates shows the data from this study to be approximately three orders of magnitude lower in nucleation rate at a given supersaturation ratio.